1. Technical Field
The present invention relates to scanning electron microscopes and similar instruments.
2. Description of the Background Art
Conventional Critical-Dimension Scanning Electron Microscopes (CD-SEMs) and electron beam (e-beam) Defect Review instruments (eDRs) generally capture only planar information about the surface of a feature on a wafer. The depth information, such as from walls of the feature, are typically not obtained by such CD-SEMs and eDRs.
It is desirable to obtain depth information, in addition to planar information, about features on a substrate surface. Such depth information is useful both for critical dimension measurements and for defect review.
Note that the diagrams in the present application are presented for explanatory purposes and are not necessarily to scale.